Can't change my apple ID because it is my apple email rescue address - how do I change the apple e mail rescue address?

Follow steps 1 to 7 half-way down the page that you posted from, that will let you edit your rescue email address

I have the same problem on my mac. What is the page the person would have posted from so I can follow those steps 1-7?

The page that the original poster posted from has been removed, this is the current page : Manage your Apple ID primary, rescue, alternate, and notification email addresses - Apple Support

i.e. you can change the rescue email address by logging into the account via the 'manage your apple id' button on http://appleid.apple.com, select the Password & Security section of your account, answer your security questions on that scree, and you should get a screen where you can change the rescue email address (plus the security questions)

can you help me please

You already know that you are only talking to fellow users on here, not iTunes Support nor Apple.

If you remember your answers to your security questions : About your Apple ID email addresses - Apple Support

If you can't remember : If you forgot the answers to your Apple ID security questions - Apple Support